System and method for protection against malicious program code injection

ABSTRACT

A system, apparatus, method, and machine-readable medium are described for defending against malicious code injection. For example, one embodiment of an apparatus comprises: a processor to execute an application to access a web page on the Internet in response to user input, the web page having one or more resource descriptors and/or code descriptors associated therewith; an authenticator engine to validate the web page based, at least in part, on the resource descriptors and/or code descriptors, by connecting to a trusted entity; and wherein the trusted entity is configured to generate a signature on a cryptographic assertion that includes one or more resource descriptor objects associated with the one or more resource descriptors and/or one or more code descriptor objects associated with the one or more code descriptors.

BACKGROUND Field of the Invention

This invention relates generally to the field of data processing systems. More particularly, the invention relates to a system and method for protecting against malicious program code injection such as JavaScript injection.

Description of Related Art

FIG. 1 illustrates an exemplary client 120 with a biometric device 100. When operated normally, a biometric sensor 102 reads raw biometric data from the user (e.g., capture the user's fingerprint, record the user's voice, snap a photo of the user, etc) and a feature extraction module 103 extracts specified characteristics of the raw biometric data (e.g., focusing on certain regions of the fingerprint, certain facial features, etc). A matcher module 104 compares the extracted features 133 with biometric reference data 110 stored in a secure storage on the client 120 and generates a score based on the similarity between the extracted features and the biometric reference data 110. The biometric reference data 110 is typically the result of an enrollment process in which the user enrolls a fingerprint, voice sample, image or other biometric data with the device 100. An application 105 may then use the score to determine whether the authentication was successful (e.g., if the score is above a certain specified threshold).

While the system shown in FIG. 1 is oriented towards biometric authentication, various other or additional authentication techniques may be employed on the exemplary client 120. For example, the client-side authenticators may be based on a PIN or other secret code (e.g., a password) entered by the user and/or may be triggered based on user presence (e.g., a button that user pushes to verify presence).

Systems have been designed for providing secure user authentication over a network using biometric sensors. In such systems, the score generated by the application, and/or other authentication data, may be sent over a network to authenticate the user with a remote server. For example, Patent Application No. 2011/0082801 (“'801 Application”) describes a framework for user registration and authentication on a network which provides strong authentication (e.g., protection against identity theft and phishing), secure transactions (e.g., protection against “malware in the browser” and “man in the middle” attacks for transactions), and enrollment/management of client authentication tokens (e.g., fingerprint readers, facial recognition devices, smartcards, trusted platform modules, etc).

The assignee of the present application has developed a variety of improvements to the authentication framework described in the '801 application. Some of these improvements are described in the following set of U.S. patent applications (“Co-pending Applications”), all filed Dec. 29, 1012, which are assigned to the present assignee and incorporated herein by reference: Ser. No. 13/730,761, Query System and Method to Determine Authentication Capabilities; Ser. No. 13/730,776, System and Method for Efficiently Enrolling, Registering, and Authenticating With Multiple Authentication Devices; Ser. No. 13/730,780, System and Method for Processing Random Challenges Within an Authentication Framework; Ser. No. 13/730,791, System and Method for Implementing Privacy Classes Within an Authentication Framework; Ser. No. 13/730,795, System and Method for Implementing Transaction Signaling Within an Authentication Framework.

Briefly, the Co-Pending Applications describe authentication techniques in which a user enrolls with authentication devices (or Authenticators) such as biometric devices (e.g., fingerprint sensors) on a client device. When a user enrolls with a biometric device, biometric reference data is captured (e.g., by swiping a finger, snapping a picture, recording a voice, etc). The user may subsequently register the authentication devices with one or more servers over a network (e.g., Websites or other relying parties equipped with secure transaction services as described in the Co-Pending Applications); and subsequently authenticate with those servers using data exchanged during the registration process (e.g., cryptographic keys provisioned into the authentication devices). Once authenticated, the user is permitted to perform one or more online transactions with a Website or other relying party. In the framework described in the Co-Pending Applications, sensitive information such as fingerprint data and other data which can be used to uniquely identify the user, may be retained locally on the user's authentication device to protect a user's privacy.

BRIEF DESCRIPTION OF THE DRAWINGS

A better understanding of the present invention can be obtained from the following detailed description in conjunction with the following drawings, in which:

FIG. 1 illustrates an exemplary client device having biometric authentication capabilities;

FIGS. 2A-B illustrate two different embodiments of a secure authentication system architecture;

FIG. 2C illustrates a transaction diagram showing how keys may be registered into authentication devices;

FIGS. 3A-B illustrates embodiments for secure transaction confirmation using a secure display;

FIG. 4 illustrate one embodiment of the invention for performing authentication for a transaction with a device without established relation;

FIGS. 5A-B are transaction diagrams showing two different embodiments for performing authentication for a transaction;

FIG. 6 illustrates additional architectural features employed in one embodiment of the invention;

FIGS. 7-8 illustrate different embodiments of bearer tokens employed in different embodiments of the invention;

FIG. 9 illustrates exemplary “offline” and “semi-offline” authentication scenarios;

FIG. 10 illustrates an exemplary system architecture for clients and/or servers;

FIG. 11 illustrates another exemplary system architecture for clients and/or servers;

FIG. 12 illustrates a man-in-the-middle (MITM) arrangement between a client and a server;

FIG. 13 illustrates an example set of interactions when a client visits a web page;

FIG. 14 illustrates an MITM capturing communication related to the web page and subsequent JavaScript links;

FIG. 15 illustrates an MITM interposed between the client and server during an authentication stage; and

FIG. 16 illustrates one embodiment of a client-server authentication using resource descriptors and code descriptors.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Described below are embodiments of an apparatus, method, and machine-readable medium for implementing advanced authentication techniques and associated applications. Throughout the description, for the purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the present invention. It will be apparent, however, to one skilled in the art that the present invention may be practiced without some of these specific details. In other instances, well-known structures and devices are not shown or are shown in a block diagram form to avoid obscuring the underlying principles of the present invention.

The embodiments of the invention discussed below involve client devices with authentication capabilities such as biometric devices or PIN entry. These devices are sometimes referred to herein as “tokens,” “authentication devices,” or “authenticators.” While certain embodiments focus on facial recognition hardware/software (e.g., a camera and associated software for recognizing a user's face and tracking a user's eye movement), some embodiments may utilize additional biometric devices including, for example, fingerprint sensors, voice recognition hardware/software (e.g., a microphone and associated software for recognizing a user's voice), and optical recognition capabilities (e.g., an optical scanner and associated software for scanning the retina of a user). The authentication capabilities may also include non-biometric devices such as trusted platform modules (TPMs) and smartcards.

In a mobile biometric implementation, the biometric device may be remote from the relying party. As used herein, the term “remote” means that the biometric sensor is not part of the security boundary of the computer it is communicatively coupled to (e.g., it is not embedded into the same physical enclosure as the relying party computer). By way of example, the biometric device may be coupled to the relying party via a network (e.g., the Internet, a wireless network link, etc) or via a peripheral input such as a USB port. Under these conditions, there may be no way for the relying party to know if the device is one which is authorized by the relying party (e.g., one which provides an acceptable level of authentication and integrity protection) and/or whether a hacker has compromised the biometric device. Confidence in the biometric device depends on the particular implementation of the device.

However, as discussed below, the authentication techniques employed to authenticate the user may involve non-location components such as communication over a network with remote servers and/or other data processing devices. Moreover, while specific embodiments are described herein (such as an ATM and retail location) it should be noted that the underlying principles of the invention may be implemented within the context of any system in which a transaction is initiated locally or remotely by an end user.

The term “relying party” is sometimes used herein to refer, not merely to the entity with which a user transaction is attempted (e.g., a Website or online service performing user transactions), but also to the secure transaction servers implemented on behalf of that entity which may performed the underlying authentication techniques described herein. The secure transaction servers which provided remote authentication capabilities may be owned and/or under the control of the relying party or may be under the control of a third party offering secure transaction services to the relying party as part of a business arrangement.

The term “server” is used herein to refer to software executed on a hardware platform (or across multiple hardware platforms) that receives requests over a network from a client, responsively performs one or more operations, and transmits a response to the client, typically including the results of the operations. The server responds to client requests to provide, or help to provide, a network “service” to the clients. Significantly, a server is not limited to a single computer (e.g., a single hardware device for executing the server software) and may, in fact, be spread across multiple hardware platforms, potentially at multiple geographical locations.

The embodiments of the invention described herein include techniques for authenticating a user for a transaction initiated through a secure transaction device. By way of example, the transaction may be a withdrawal, transfer, or other user-initiated operation and the transaction device may be an automatic teller machine (ATM), point-of-sale (PoS) transaction device or other device capable of executing transactions on behalf of the user. The transaction may involve, for example, completing a payment to purchase goods or services at a retail store or other retail location equipped with the device, withdrawing funds via the device, performing maintenance on the device, or any other transaction for which user authentication is required.

One embodiment of the invention provides techniques for authenticating the user locally (i.e. verifying the user), even in circumstances where the device is offline (i.e., not connected to a back-end authentication server) or semi-offline (i.e., only periodically connected to a back-end authentication server). In one embodiment, the user's client device is provided with the ability to cache authentication requests generated by a back-end authentication server (e.g., operated on behalf of the relying party) and the device is provided with data needed to verify the authentication response transmitted from the user's client device to the device.

Prior to discussing the details of these embodiments of the invention, an overview of remote user authentication techniques will be provided. These and other remote user authentication techniques are described in the co-pending applications, which are assigned to the assignee of the present application and incorporated herein by reference.

Remote User Authentication Techniques

FIGS. 2A-B illustrate two embodiments of a system architecture comprising client-side and server-side components for remotely authenticating a user. The embodiment shown in FIG. 2A uses a browser plugin-based architecture for communicating with a website while the embodiment shown in FIG. 2B does not require a browser. The various authentication techniques and associated applications described herein may be implemented on either of these system architectures. For example, the authentication engines within client devices described herein may be implemented as part of the secure transaction service 201 including interface 202. It should be noted, however, that the embodiments described above may be implemented using logical arrangements of hardware and software other than those shown in FIGS. 2A-B.

Turning to FIG. 2A, the illustrated embodiment includes a client 200 equipped with one or more authentication devices 210-212 for enrolling and authenticating an end user. As mentioned above, the authentication devices 210-212 may include biometric devices such as fingerprint sensors, voice recognition hardware/software (e.g., a microphone and associated software for recognizing a user's voice), facial recognition hardware/software (e.g., a camera and associated software for recognizing a user's face), and optical recognition capabilities (e.g., an optical scanner and associated software for scanning the retina of a user) and non-biometric devices such as a trusted platform modules (TPMs) and smartcards. A user may enroll the biometric devices by providing biometric data (e.g., swiping a finger on the fingerprint device) which the secure transaction service 201 may store as biometric template data in secure storage 220 (via interface 202).

While the secure storage 220 is illustrated outside of the secure perimeter of the authentication device(s) 210-212, in one embodiment, each authentication device 210-212 may have its own integrated secure storage. Additionally, each authentication device 210-212 may cryptographically protect the biometric reference data records (e.g., wrapping them using a symmetric key to make the storage 220 secure).

The authentication devices 210-212 are communicatively coupled to the client through an interface 202 (e.g., an application programming interface or API) exposed by a secure transaction service 201. The secure transaction service 201 is a secure application for communicating with one or more secure transaction servers 232-233 over a network and for interfacing with a secure transaction plugin 205 executed within the context of a web browser 204. As illustrated, the Interface 202 may also provide secure access to a secure storage device 220 on the client 200 which stores information related to each of the authentication devices 210-212 such as a device identification code (such as an Authenticator Attestation ID (AAID)), user identification code, user enrollment data (e.g., scanned fingerprint or other biometric data), and keys used to perform the secure authentication techniques described herein. For example, as discussed in detail below, a unique key may be stored into each of the authentication devices and subsequently used when communicating to servers 230 over a network such as the Internet.

As discussed below, certain types of network transactions are supported by the secure transaction plugin 205 such as HTTP or HTTPS transactions with websites 231 or other servers. In one embodiment, the secure transaction plugin is initiated in response to specific HTML tags inserted into the HTML code of a web page by the web server 231 within the secure enterprise or Web destination 230 (sometimes simply referred to below as “server 230”). In response to detecting such a tag, the secure transaction plugin 205 may forward transactions to the secure transaction service 201 for processing. In addition, for certain types of transactions (e.g., such as secure key exchange) the secure transaction service 201 may open a direct communication channel with the on-premises transaction server 232 (i.e., co-located with the website) or with an off-premises transaction server 233.

The secure transaction servers 232-233 are coupled to a secure transaction database 240 for storing user data, authentication device data, keys and other secure information needed to support the secure authentication transactions described below. It should be noted, however, that the underlying principles of the invention do not require the separation of logical components within the secure enterprise or web destination 230 shown in FIG. 2A. For example, the website 231 and the secure transaction servers 232-233 may be implemented within a single physical server or separate physical servers. Moreover, the website 231 and transaction servers 232-233 may be implemented within an integrated software module executed on one or more servers for performing the functions described below.

As mentioned above, the underlying principles of the invention are not limited to a browser-based architecture shown in FIG. 2A. FIG. 2B illustrates an alternate implementation in which a stand-alone application 254 utilizes the functionality provided by the secure transaction service 201 to authenticate a user over a network. In one embodiment, the application 254 is designed to establish communication sessions with one or more network services 251 which rely on the secure transaction servers 232-233 for performing the user/client authentication techniques described in detail below.

In either of the embodiments shown in FIGS. 2A-B, the secure transaction servers 232-233 may generate the keys which are then securely transmitted to the secure transaction service 201 and stored into the authentication devices within the secure storage 220. Additionally, the secure transaction servers 232-233 manage the secure transaction database 240 on the server side.

FIG. 2C illustrates a series of transactions for registering authentication devices. As mentioned above, during registration, a key is shared between the authentication device and one of the secure transaction servers 232-233. The key is stored within the secure storage 220 of the client 200 and the secure transaction database 220 used by the secure transaction servers 232-233. In one embodiment, the key is a symmetric key generated by one of the secure transaction servers 232-233. However, in another embodiment discussed below, asymmetric keys may be used. In this embodiment, the public key may be stored by the secure transaction servers 232-233 and a second, related private key may be stored in the secure storage 220 on the client. Moreover, in another embodiment, the key(s) may be generated on the client 200 (e.g., by the authentication device or the authentication device interface rather than the secure transaction servers 232-233). The underlying principles of the invention are not limited to any particular types of keys or manner of generating the keys.

A secure key provisioning protocol such as the Dynamic Symmetric Key Provisioning Protocol (DSKPP) may be used to share the key with the client over a secure communication channel (see, e.g., Request for Comments (RFC) 6063). However, the underlying principles of the invention are not limited to any particular key provisioning protocol.

Turning to the specific details shown in FIG. 2C, once the user enrollment or user verification is complete, the server 230 generates a randomly generated challenge (e.g., a cryptographic nonce) that must be presented by the client during device registration. The random challenge may be valid for a limited period of time. The secure transaction plugin detects the random challenge and forwards it to the secure transaction service 201. In response, the secure transaction service initiates an out-of-band session with the server 230 (e.g., an out-of-band transaction) and communicates with the server 230 using the key provisioning protocol. The server 230 locates the user with the user name, validates the random challenge, validates the device's attestation code (e.g., AAID) if one was sent, and creates a new entry in the secure transaction database 220 for the user. It may also generate the key or public/private key pair, write the key(s) to the database 220 and send the key(s) back to the secure transaction service 201 using the key provisioning protocol. Once complete, the authentication device and the server 230 share the same key if a symmetric key was used or different keys if asymmetric keys were used.

FIG. 3A illustrates a secure transaction confirmation for a browser-based implementation. While a browser-based implementation is illustrated, the same basic principles may be implemented using a stand-alone application or mobile device app.

The secure transaction confirmation is designed to provide stronger security for certain types of transactions (e.g., financial transactions). In the illustrated embodiment, the user confirms each transaction prior to committing the transaction. Using the illustrated techniques, the user confirms exactly what he/she wants to commit and commits exactly what he/she sees displayed in a window 301 of the graphical user interface (GUI). In other words, this embodiment ensures that the transaction text cannot be modified by a “man in the middle” (MITM) or “man in the browser” (MITB) to commit a transaction which the user did not confirm.

In one embodiment, the secure transaction plugin 205 displays a window 301 in the browser context to show the transaction details. The secure transaction server 201 periodically (e.g., with a random interval) verifies that the text that is shown in the window is not being tampered by anyone (e.g., by generating a hash/signature over the displayed text). In a different embodiment, the authentication device has a trusted user interface (e.g. providing an API compliant to GlobalPlatform's TrustedUI).

The following example will help to highlight the operation of this embodiment. A user chooses items for purchase from a merchant site and selects “check out.” The merchant site sends the transaction to a service provide which has a secure transaction server 232-233 implementing one or more of the embodiments of the invention described herein (e.g., PayPal). The merchant site authenticates the user and completes the transaction.

The secure transaction server 232-233 receives the transaction details (TD) and puts a “Secure Transaction” request in an HTML page and sends to client 200. The Secure Transaction request includes the transaction details and a random challenge. The secure transaction plugin 205 detects the request for transaction confirmation message and forwards all data to the secure transaction service 201. In an embodiment which does not use a browser or plugin, the information may be sent directly from the secure transaction servers to the secure transaction service on the client 200.

For a browser-based implementation, the secure transaction plugin 205 displays a window 301 with transaction details to the user (e.g. in a browser context) and asks the user to provide authentication to confirm the transaction. In an embodiment which does not use a browser or plugin, the secure transaction service 201, the application 254 (FIG. 2B), or the authentication device 210 may display the window 301. The secure transaction service 201 starts a timer and verifies the content of the window 301 being displayed to the user. The period of verification may be randomly chosen. The secure transaction service 201 ensures that user sees the valid transaction details in the window 301 (e.g., generating a hash on the details and verifying that the contents are accurate by comparing against a hash of the correct contents). If it detects that the content has been tampered with it prevents the confirmation token/signature from being generated.

After the user provides valid verification data (e.g. by, swiping a finger on the fingerprint sensor), the authentication device verifies the user and generates a cryptographic signature (sometimes referred to as a “token”) with the transaction details and the random challenge (i.e., the signature is calculated over the transaction details and the nonce). This allows the secure transaction server 232-233 to ensure that the transaction details have not been modified between the server and the client. The secure transaction service 201 sends the generated signature and username to the secure transaction plugin 205 which forwards the signature to the secure transaction server 232-233. The secure transaction server 232-233 identifies the user with the username and verifies the signature. If verification succeeds, a confirmation message is sent to the client and the transaction is processed.

One embodiment of the invention implements a query policy in which a secure transaction server transmits a server policy to the client indicating the authentication capabilities accepted by the server. The client then analyzes the server policy to identify a subset of authentication capabilities which it supports and/or which the user has indicated a desire to use. The client then registers and/or authenticates the user using the subset of authentication tokens matching the provided policy. Consequently, there is a lower impact to the client's privacy because the client is not required to transmit exhaustive information about its authentication capabilities (e.g., all of its authentication devices) or other information which might be used to uniquely identify the client.

By way of example, and not limitation, the client may include numerous user verification capabilities such as a fingerprint sensor, voice recognition capabilities, facial recognition capabilities, eye/optical recognition capabilities, PIN verification, to name a few. However, for privacy reasons, the user may not wish to divulge the details for all of its capabilities to a requesting server. Thus, using the techniques described herein, the secure transaction server may transmit a server policy to the client indicating that it supports, for example, fingerprint, optical, or smartcard authentication. The client may then compare the server policy against its own authentication capabilities and choose one or more of the available authentication options.

One embodiment of the invention employs transaction signing on the secure transaction server so that no transaction state needs to be maintained on the server to maintain sessions with clients. In particular, transaction details such as transaction text displayed within the window 301 may be sent to the client signed by the server. The server may then verify that the signed transaction responses received by the client are valid by verifying the signature. The server does not need to persistently store the transaction content, which would consume a significant amount of storage space for a large number of clients and would open possibility for denial of service type attacks on server.

One embodiment of the invention is illustrated in FIG. 3B which shows a website or other network service 311 initiating a transaction with a client 200. For example, the user may have selected items for purchase on the website and may be ready to check out and pay. In the illustrated example, the website or service 311 hands off the transaction to a secure transaction server 312 which includes signature processing logic 313 for generating and verifying signatures (as described herein) and authentication logic for performing client authentication 314 (e.g., using the authentication techniques previously described).

In one embodiment, the authentication request sent from the secure transaction server 312 to the client 200 includes the random challenge such as a cryptographic nonce (as described above), the transaction details (e.g., the specific text presented to complete the transaction), and a signature generated by the signature processing logic 313 over the random challenge and the transaction details using a private key (known only by the secure transaction server).

Once the above information is received by the client, the user may receive an indication that user verification is required to complete the transaction. In response, the user may, for example, swipe a finger across a fingerprint scanner, snap a picture, speak into a microphone, or perform any other type of authentication permitted for the given transaction. In one embodiment, once the user has been successfully verified by the authentication device 210, the client transmits the following back to the server: (1) the random challenge and transaction text (both previously provided to the client by the server), (2) authentication data proving that the user successfully completed authentication, and (3) the signature.

The authentication module 314 on the secure transaction server 312 may then confirm that the user has correctly authenticated and the signature processing logic 313 re-generates the signature over the random challenge and the transaction text using the private key. If the signature matches the one sent by the client, then the server can verify that the transaction text is the same as it was when initially received from the website or service 311. Storage and processing resources are conserved because the secure transaction server 312 is not required to persistently store the transaction text (or other transaction data) within the secure transaction database 120.

System and Method for Authenticating a Client to an Offline Device or a Device Having Limited Connectivity

As mentioned, one embodiment of the invention includes techniques for authenticating the user locally (i.e. verifying the user), even in circumstances where the user device and device are offline (i.e., not connected to a back-end authentication server of a relying party) or semi-offline (i.e., where the user device is not connected to the relying party, but the device is). FIG. 4 illustrates one such arrangement in which a client 400 with authentication devices previously registered with a relying party 451 establishes a secure channel with a transaction device 450 to complete a transaction. By way of example, and not limitation, the transaction device may be an ATM, point-of-sale (PoS) transaction device at a retail location, Internet of Things (IoT) device, or any other device capable of establishing a channel with the client 400 and allowing the user to perform a transaction. The channel may be implemented using any wireless communication protocol including, by way of example and not limitation, near field communications (NFC) and Bluetooth (e.g., Bluetooth Low Energy (BTLE) as set forth in the Bluetooth Core Specification Version 4.0). Of course, the underlying principles of the invention are not limited to any particular communication standard.

As indicated by the dotted arrows, the connection between the client 400 and the relying party 451 and/or the connection between the transaction device 450 and the relying party 451 may be sporadic or non-existent. Real world applications in the area of payments often rely on such “off-line” use-cases. For example, a user with a client 400 (e.g., a Smartphone) may not have connectivity to the relying party 451 at the time of the transaction but may want to authorize a transaction (e.g. a payment) by authenticating to the transaction device 450. However, in some embodiments of the invention, the client 400 and/or transaction device 450 do exchange some information with the relying party 451 (although not necessarily during the authentication or transaction confirmation process described herein).

Traditionally, user verification has been implemented using a secret such as a personal identification number (PIN) to be captured by the device (e.g. the PoS transaction device or ATM). The device would then create an online connection to the relying party in order to verify the secret or would ask the user's authenticator (e.g., EMV banking card) for verifying the PIN. Such implementation has several disadvantages. It might require an online connection—which might be available sometimes, but not always. It also requires the user to enter a long-term valid secret into potentially untrusted devices, which are subject to shoulder-surfing and other attacks. Additionally it is inherently tied to the specific user verification method (e.g. PIN in this case). Finally, it requires the user to remember a secret such as a PIN, which may be inconvenient to the user.

The authentication techniques described herein provide significantly more flexibility in terms of user verification methods and security as they allow the user to rely on his/her own client's authentication capabilities. In particular, in one embodiment, a mobile application on the user's client caches authentication requests provided by the relying party during a time when the client is connected to the relying party. The authentication requests may include the same (or similar) information as the authentication requests described above (e.g., a nonce and a public key associated with an authenticator) as well as additional information including a signature over (at least parts of) the authentication request generated by a relying party, the verification key and potentially timing data indicating the time period within which the authentication request will remain valid (or conversely, the time after which the authentication request will expire). In one embodiment, the mobile application may cache multiple such connection requests (e.g., one for each transaction device or transaction device type).

In one embodiment, the cached authentication requests may then be used for transactions with the transaction device, in circumstances where the client/mobile app is incapable of connecting with the relying party. In one embodiment, the mobile app triggers the creation of the authentication response based on the cached authentication request containing the serverData and additional data received from the transaction device. The authentication response is then transmitted to the transaction device which then verifies the authentication response using a verification key provided from the relying party (e.g., during a time when the transaction device is connected with the relying party). In particular, the transaction device may use the key provided by the relying party to verify the signature over the serverData included in the authentication response. In one embodiment, the signature is generated by the relying party using a private relying party verification key and the transaction device verifies the signature using a corresponding public relying party verification key (provided to the transaction device by the relying party).

Once the transaction device verifies the serverData extracted from the authentication response, it may then use the public key extracted from the authentication request (e.g., Uauth.pub) to verify the authentication response generated by the client/mobile app (e.g., in the same or a similar manner to the verifications by the relying party described above, when the client is authenticating directly to the relying party).

In an alternate embodiment described below, the relying party provides the authentication request directly to the transaction device (rather than through the mobile app on the client device). In this embodiment, the transaction device may ask for the authentication request from the relying party upon receiving a request to complete a transaction from the mobile app on the client. Once it has the authentication request, it may validate the request and the authentication response as described above (e.g., by generating a signature and comparing it to the existing signature).

FIG. 5A is a transaction diagram showing interactions between the client 400, transaction device 450 and relying party in an embodiment in which the client 400 caches the authentication request. This embodiment is sometimes referred to as the “full-offline” embodiment because it does not require the transaction device 450 to have an existing connection with the relying party.

At 501, the client requests a cacheable authentication request from the relying party. At 502, the relying party generates the cacheable authentication request, at 503 the authentication request is sent to the client, and at 504 the client caches the authentication request. In one embodiment, the authentication request includes the public key associated with the authenticator to be used for authentication (Uauth.pub) and a signature generated using the relying party verification key (RPVerifyKey) over the public key and a random nonce. If asymmetric keys are used, then RPVerifyKey used by the relying party to generate the signature is a private key having a corresponding public RPVerifyKey which the relying party has provided to the transaction device (potentially far in advance of processing the user authentication request).

In one embodiment, the authentication request also includes timing information indicating the length of time for which the authentication request will be valid (e.g., MaxCacheTime). In this embodiment, the signature for the cacheable authentication request may be generated over the combination of the public authentication key, the nonce, and the MaxCacheTime (e.g., ServerData=Uauth.pub|MaxCacheTime|serverNonce|Sign (RPVerifyKey, Uauth.pub|MaxCacheTime|serverNonce)). In one embodiment, the authentication response includes more than one authentication key (e.g., one for each authenticator capable of authenticating the user) and the signature may be generated over all of these keys (e.g., along with the nonce and the MaxCacheTime).

As mentioned, the public RPVerifyKey needs to be known the transaction device 450, or any device intended to perform offline verification of the authentication requests/responses. This extension is required because the transaction device does not have any knowledge about the authentication keys registered at the relying party (i.e. no established relation exists between user device and the transaction device). Consequently, the relying party must communicate to the transaction device (or other device), in a secure manner, which key(s) are to be used for authentication response verification. The transaction device will verify the MaxCacheTime to determine whether the cached authentication request is still valid (to comply with the relying party's policy on how long the cached authentication request may be used).

At 505, the client establishes a secure connection to the transaction device and initiates a transaction. For example, if the transaction device is a PoS transaction device, the transaction may involve a debit or credit transaction. If the transaction device is an ATM, the transaction may involve a cash withdrawal or a maintenance task. The underlying principles of the invention are not limited to any particular type of transaction device or secure connection. In addition, at 505, the client may transmit the cached authentication request to the transaction device.

In response, at 506 the transaction device may transmit device identity information (e.g., a transaction device identification code), a random challenge (nonce) and optionally transaction text in a defined syntax to complete the transaction. The random challenge/nonce will then be cryptographically bound to the authentication response. This mechanism allows the device to verify that the user verification is fresh and hasn't been cached/reused.

In order to support transaction confirmations such as described above (see, e.g., FIGS. 3A-B and associated text), the transaction device may be required to create a standardized, and human readable representation of the transaction. “Standardized” as used herein means a format that can be parsed by the relying party (e.g. for final verification as indicated in operation 511 below) and/or the transaction device. It needs to be human readable because transaction confirmations require the authenticator to display it on the secure display of the client 400. An example of such an encoding could be XML where XSLT is used for visualization.

At 507, to generate the authentication response, an authentication user interface is displayed directing the user to perform authentication on the client using a particular authenticator (e.g., to swipe a finger on a fingerprint sensor, enter a PIN code, speak into a microphone, etc). Once the user provides authentication, the authentication engine on the client verifies the identity of the user (e.g., comparing the authentication data collected from the user with the user verification reference data stored in the secure storage of the authenticator) and uses the private key associated with the authentication device to encrypt and/or generate a signature over the random challenge (and also potentially the transaction device ID and/or the transaction text). The authentication response is then transmitted to the transaction device at 508.

At 509, the transaction device uses the public RPVerifyKey to verify the signature on the serverData (received at 505) if it has not done so already. Once the serverData is verified, it knows the public key associated with the authenticator used to perform the authentication (Uauth.pub). It uses this key to verify the authentication response. For example, it may use the public authentication key to decrypt or verify the signature generated over the nonce and any other related information (e.g., the transaction text, the transaction device ID, etc). If transaction confirmation is performed by the transaction device, then it may verify the transaction text displayed on the client by validating the signature generated over the transaction text and included in the authentication response at 508. Instead of having a cryptographically secured serverData structure, the transaction device could also verify unsigned serverData using an online connection to the relying party—if this is available (semi-offline case).

At 510, a success or failure indication is sent to the client depending on whether authentication was successful or unsuccessful, respectively. If successful, the transaction device will permit the transaction (e.g., debiting/crediting an account to complete a purchase, dispensing cash, performing administrative task, etc). If not, it will disallow the transaction and/or request additional authentication.

If a connection to the relying party is present, then at 511 the transaction device may transmit the authentication response to the relying party and/or the transaction text (assuming that the relying party is the entity responsible for verifying the transaction text). A record of the transaction may be recorded at the relying party and/or the relying party may verify the transaction text and confirm the transaction (not shown).

FIG. 5B is a transaction diagram showing interactions between the client 400, transaction device 450 and relying party in an embodiment in which the transaction device has a connection with and receives the authentication request from the relying party. This embodiment is sometimes referred to as the “semi-offline” embodiment because although the client does not have a connection to the relying party, the transaction device 450 does.

At 521, the client initiates a transaction, establishing a secure connection with the transaction device (e.g., NFC, Bluetooth, etc). At 522, the transaction device responsively asks for an authentication request from the relying party. At 523, the relying party generates the authentication request and at 524 the authentication request is sent to the transaction device. As in the embodiment shown in FIG. 5A, the authentication request may include the public key associated with the authenticator on the client to be used for authentication (Uauth.pub) and a signature generated using the relying party verification key (RPVerifyKey) over the public key and a random nonce. If asymmetric keys are used, then RPVerifyKey used by the relying party to generate the signature is a private key having a corresponding public RPVerifyKey which the relying party provides to the transaction device (potentially far in advance of processing the user authentication request). Instead of having a cryptographically secured serverData structure, the transaction device may also verify unsigned serverData using an online connection to the relying party—if this is available (semi-offline case).

In one embodiment, the serverData also includes timing information indicating the length of time for which the authentication request will be valid (e.g., MaxCacheTime). In this embodiment, the signature for the serverData may be generated over the combination of the public authentication key, the nonce, and the MaxCacheTime (e.g., ServerData=Uauth.pub|MaxCacheTime|serverNonce|Sign (RPVerifyKey, Uauth.pub|MaxCacheTime|serverNonce)). In one embodiment, the authentication response includes more than one authentication key (e.g., one for each authenticator) and the signature may be generated over all of these keys (e.g., along with the nonce and the MaxCacheTime).

In one embodiment, the remainder of the transaction diagram in FIG. 5B operates substantially as shown in FIG. 5A. At 525 the transaction device may transmit identity information (e.g., a transaction device identification code), a random challenge (nonce) and optionally transaction text in a defined syntax to complete the transaction. The random challenge/nonce will then be cryptographically bound to the authentication response. This mechanism allows the device to verify that the user verification is fresh and hasn't been cached.

In order to support transaction confirmations such as described above (see, e.g., FIGS. 3A-B and associated text), the transaction device may be required to create a standardized, and human readable representation of the transaction. “Standardized” as used herein means a format that can be parsed by the relying party (e.g. for final verification as indicated in operation 511 below) and/or the transaction device. It needs to be human readable because transaction confirmations require the authenticator to display it on the secure display of the client 400. An example of such an encoding could be XML where XSLT is used for visualization.

At 526, to generate the authentication response, an authentication user interface is displayed directing the user to perform authentication on the client using a particular authenticator (e.g., to swipe a finger on a fingerprint sensor, enter a PIN code, speak into a microphone, etc). Once the user provides authentication, the authentication engine on the client verifies the identity of the user (e.g., comparing the authentication data collected from the user with the user verification reference data stored in the secure storage of the authenticator) and uses the private key associated with the authentication device to encrypt and/or generate a signature over the random challenge (and also potentially the transaction device ID and/or the transaction text). The authentication response is then transmitted to the transaction device at 527.

At 528, the transaction device uses the public RPVerifyKey to verify the signature on the serverData (received at 524) if it has not done so already. Once the serverData is verified, it knows the public key associated with the authenticator used to perform the authentication (Uauth.pub). It uses this key to verify the authentication response. For example, it may use the public authentication key to decrypt or verify the signature generated over the nonce and any other related information (e.g., the transaction text, the transaction device ID, etc). If transaction confirmation is performed by the transaction device, then it may verify the transaction text displayed on the client by validating the signature generated over the transaction text and included in the authentication response at 528. Instead of having a cryptographically secured serverData structure, the transaction device could also verify unsigned serverData using an online connection to the relying party—if this is available (semi-offline case).

At 529, a success or failure indication is sent to the client depending on whether authentication was successful or unsuccessful, respectively. If successful, the transaction device will permit the transaction (e.g., debiting/crediting an account to complete a purchase, dispensing cash, performing administrative task, etc). If not, it will disallow the transaction and/or request additional authentication.

At 530 the transaction device may transmit the authentication response to the relying party and/or the transaction text (assuming that the relying party is the entity responsible for verifying the transaction text). A record of the transaction may be recorded at the relying party and/or the relying party may verify the transaction text and confirm the transaction (not shown).

As illustrated in FIG. 6, in one embodiment, a mobile app 601 is executed on the client to perform the operations described herein in combination with an authentication client 602 (which may be the secure transaction service 201 and interface 202 shown in FIG. 2B). In particular, the mobile app 601 may open a secure channel to a web app 611 executed on the transaction device 450 using transport layer security (TLS) or other secure communication protocol. A web server 612 on the transaction device may also open a secure channel to communicate with the relying party 451 (e.g., to retrieve authentication requests and/or to provide updates to the relying party 451 as discussed above). The authentication client 602 may communicate directly with the relying party 451 to, for example, retrieve cacheable authentication requests (as discussed in detail above).

In one embodiment, the authentication client 602 may identify the relying party and any authorized Mobile Apps 601 with an “AppID” which is a unique code associated with each application made available by a relying party. In some embodiments, where a relying party offers multiple online services, a user may have multiple ApplDs with a single relying party (one for each service offered by the relying party).

In one embodiment, any application identified by an AppID may have multiple “facets” which identify the allowable mechanisms and/or application types for connecting with the relying party. For example, a particular relying party may allow access via a Web service and via different platform-specific mobile apps (e.g., an Android App, an iOS App, etc). Each of these may be identified using a different “FacetID” which may be provided by the relying party to the authentication engine as illustrated.

In one embodiment, the calling mobile app 601 passes its AppID to the API exposed by the authentication client 602. On each platform, the authentication client 602 identifies the calling app 601, and determines its FacetID. It then resolves the AppID and checks whether the FacetID is included in a TrustedApps list provided by the relying party 451.

In one embodiment, the cacheable authentication requests discussed above may be implemented using bearer tokens such as illustrated in FIGS. 7 and 8. In the embodiments of the invention described herein, the token recipient (the transaction device 450), needs to be able to verify the token, the authentication response and the binding of the token to the authentication response without requiring another “online” connection to the token issuer (the relying party).

Two classes of bearer tokens should be distinguished:

1. Tokens which can only be verified by the recipient (e.g., the transaction device 450) using a different channel to the issuer (e.g., the relying party 451), that must exist between the token issuance and the token verification. This class of tokens is referred to herein as “unsigned tokens.”

2. Tokens which can be verified by the recipient due to their cryptographic structure, e.g., because they contain a digital signature which can be verified using data received from the token issuer, potentially way before the specific token was issued. This class of tokens is referred to herein as “signed tokens”.

The term “signed token structure” Is used herein to refer to both the signed token including the Uauth.pub key and the signed structure containing the token.

Binding Signed Tokens to Authentication Keys

As illustrated in FIG. 7, in one embodiment, in order to bind signed tokens to the Authentication Key, the token issuer (e.g., the relying party 451): (a) adds the Authentication public key (Uauth.pub) 702 to the to-be-signed portion 701 of the (to-be-) signed token; and (b) includes that signed token in the to-be-signed portion of the authentication response. By doing this, the token recipient (e.g., the transaction device 450) can verify the token by validating the signature 703 (e.g., the public RPVerifyKey discussed above). If the verification succeeds, it can extract the public key (Uauth.pub) and use it to verify the authentication response, as previously discussed.

Binding Unsigned Tokens to Authentication Keys

As illustrated in FIG. 8, in order to bind unsigned tokens 802 to the Authentication Key, in one embodiment, the token issuer (e.g., the relying party 451) creates a signed structure covering (at least) the original token 802 and to-be-signed data 801 which includes the authentication public key (Uauth.pub). The signed structure can be verified by validating the signature 803 using the public key related to the private signing key (e.g., the RPVerifyKey pair discussed above). This public signing key needs to be shared with the token recipient (e.g., the transaction device 450). Sharing can be done once after generation of the signing key pair, potentially way before the first signed structure was generated.

The techniques described herein support both the “full-offline” implementation (i.e., the transaction device 450 has no connection to the relying party 451 at the time of the transaction) as well as the “semi-offline” implementation (i.e., the transaction device has a connection to the relying party 451 at the time of the transaction, but the client does not.

Even in the full-offline case, the transaction device 450 is still expected to be connected via a host from time to time to the relying party 451. For example, the host may collect all responses stored in the transaction device 450 in order to send them to the relying party and may also update (if required) the list of revoked Uauth keys (e.g., the public authentication keys which have been revoked since the last connection).

Some embodiments also support pure (session) authentication as well as transaction confirmation. Even in the case of transaction confirmation, the relying party 451 can verify the transaction, if the transaction device 450 submits the transaction text along with the authentication response to the relying party 451.

There several different use cases/applications for the techniques described herein. For example:

1. Payment. A user has registered his authenticator (e.g. a smartphone) with a payment service provider (PSP). The user wants to authenticate a payment at some merchant using a Point-of-Sale device (PoS) authorized by the PSP, but the PoS doesn't have a reliable and permanent online connection to the PSP (e.g. located in a Bus). In this example, the PoS may be implemented as the transaction device 450 and the PSP may be implemented as the relying party 451 described above to allow the transaction notwithstanding the lack of a reliable and permanent connection.

2. Internet-of-Things. A company has installed several embedded devices (e.g. in a factory, building, etc.). Maintenance of such devices is performed by a technicians employed by a contracted party. For performing the maintenance the technician has to authenticate to the device in order to prove his eligibility for the task. The following assumptions are made (based on realistic frame conditions):

-   -   a. The technician cannot perform registration with each of such         devices (as there are too many of them).     -   b. There are too many technicians and too much fluctuation of         such technicians in order to keep the list of eligible         technicians up-to-date on each of the devices.     -   c. Neither the device nor the technician's computer has a         reliable network connection at the time of maintenance.

Using the techniques described above, the company can inject a trust anchor (e.g., the public RPVerifyKey) into all devices once (e.g., at installation time). Each technician then registers with the contracted party (e.g., the relying party 451 which may be the technician's employer). Using the above techniques, the technician will be able to authenticate to each device.

The embodiments of the invention described above may be implemented in any system in which a client with authentication capabilities is registered with a relying party and the authentication operation is performed between this client and a device (a) acting on behalf of the relying party and (b) being offline (i.e. not having a reliable network connection to the relying party's original server the client has been registered with) at the time of transaction. In such a case, the client receives a cacheable authentication request from the original server and caches it. Once it is required, the client computes the authentication response and sends it to the device.

In another embodiment, the client adds channel binding data (received in the authentication request) to the response in a cryptographically secure way. By doing this, the relying party's original server can verify that the request was received by a legitimate client (and not some man-in-the-middle).

In one embodiment, the relying party adds additional authenticated data to the response such as the Uauth.pub key which allows the device to verify the authentication or transaction confirmation response, without having to contact the relying party server for retrieving the approved Uauth.pub key. In another embodiment, the relying party requires the user of the client to perform a successful authentication before issuing the “cacheable” authentication requests (in order to prevent denial of service attacks). In one embodiment, the relying party requires the client to indicate whether a request needs to be cacheable or not. If cacheable, the relying party may require additional authentication data in the response (e.g., the MaxCacheTime discussed above).

In one embodiment, a device such as the transaction device 450 does not have a direct network connection to the relying party and is “synchronized” to the relying party using a separate computer (sometimes referred to herein as the “host”). This host retrieves all collected authentication responses from the device and transfers them to the relying party. Additionally the host may also copy a list of revoked Uauth keys to the device to ensure that one of the revoked keys is not used in an authentication response.

In one embodiment, a device such as the transaction device 450 sends a random value (e.g., nonce) to the client and the client cryptographically adds this random value as an extension to the authentication response before signing it. This signed random value serves as a freshness proof to the device.

In one embodiment, the client's authenticator adds the current time Ta as an extension to the authentication response before signing it. The device/transaction device may compare that time to the current time Td and only accept the response if the difference between Ta and Td is acceptable (e.g., if the difference is less than two minutes (abs(Td−Ta)<2 min)).

In one embodiment, the relying party adds an authenticated (i.e., signed) expiration time to the cacheable request. As discussed above, the device/transaction device will only accept the response as valid if it is received before the expiration time.

In one embodiment, the relying party adds an authenticated (i.e., signed) data block (e.g., the “signed token structure” mentioned above) including additional information such as (but not limited to) public key, expiration time, maximum transaction value (e.g., Security Assertion Markup Language (SAML) assertions, OAuth tokens, JSON Web Signature (JWS) objects, etc) to the cacheable request. The device/transaction device may only accept the response as valid if the signed data block can be positively verified and the contents are acceptable.

In one embodiment, the relying party only adds the unsigned token to the cacheable authentication request, but the transaction device has an online connection to the relying party at the time of transaction. The transaction device verifies the authenticity of the unsigned token using the online connection to the relying party at the time of transaction.

FIG. 9 illustrates exemplary “offline” and “semi-offline” authentication scenarios in accordance with one embodiment of the invention. In this embodiment, the user with a computing device 910 has an established relation to the relying party 930 and could authenticate to the relying party. However, in some circumstances, the user wants to perform a transaction (e.g., an authentication of a transaction confirmation) with a device 970 which has an established relation to the relying party 930 but not necessarily one to the user's computing device 910. With respect to this embodiment, the transaction is referred to as “full offline” if the connection 920 and connection 921 do not exist or are not stable at the relevant time (e.g., the time of authentication of the user's computing device 910 to the device 970 or of the transaction between the user's computing device 910 and the device 970). With respect to this embodiment, the transaction is “semi-offline” if the connection 920 between the user's computing device 910 and the relying party 930 is not stable, but the connection 921 between the device 970 and the relying party 930 is stable. Note that in this embodiment, connection 922 between the user's computing device 910 and device 970 is required to be stable at the relevant time. It is also expected that the Authenticator to be connected to the user's computing device 910. The connection 922 could be implemented using any type of communication channels/protocols including, but not limited to, Bluetooth, Bluetooth low energy (BTLE), near field communication (NFC), Wifi, Global System for Mobile Communications (GSM), Universal Mobile Telecommunications System (UTMS), Long-Term Evolution (LTE) (e.g., 4G LTE), and TCP/IP.

Exemplary Data Processing Devices

FIG. 10 is a block diagram illustrating an exemplary clients and servers which may be used in some embodiments of the invention. It should be understood that while FIG. 10 illustrates various components of a computer system, it is not intended to represent any particular architecture or manner of interconnecting the components as such details are not germane to the present invention. It will be appreciated that other computer systems that have fewer components or more components may also be used with the present invention.

As illustrated in FIG. 10, the computer system 1000, which is a form of a data processing system, includes the bus(es) 1050 which is coupled with the processing system 1020, power supply 1025, memory 1030, and the nonvolatile memory 1040 (e.g., a hard drive, flash memory, Phase-Change Memory (PCM), etc.). The bus(es) 1050 may be connected to each other through various bridges, controllers, and/or adapters as is well known in the art. The processing system 1020 may retrieve instruction(s) from the memory 1030 and/or the nonvolatile memory 1040, and execute the instructions to perform operations as described above. The bus 1050 interconnects the above components together and also interconnects those components to the optional dock 1060, the display controller & display device 1070, Input/Output devices 1080 (e.g., NIC (Network Interface Card), a cursor control (e.g., mouse, touchscreen, touchpad, etc.), a keyboard, etc.), and the optional wireless transceiver(s) 1090 (e.g., Bluetooth, WiFi, Infrared, etc.).

FIG. 11 is a block diagram illustrating an exemplary data processing system which may be used in some embodiments of the invention. For example, the data processing system 190 may be a handheld computer, a personal digital assistant (PDA), a mobile telephone, a portable gaming system, a portable media player, a tablet or a handheld computing device which may include a mobile telephone, a media player, and/or a gaming system. As another example, the data processing system 1100 may be a network computer or an embedded processing device within another device.

According to one embodiment of the invention, the exemplary architecture of the data processing system 1100 may be used for the mobile devices described above. The data processing system 1100 includes the processing system 1120, which may include one or more microprocessors and/or a system on an integrated circuit. The processing system 1120 is coupled with a memory 1110, a power supply 1125 (which includes one or more batteries) an audio input/output 1140, a display controller and display device 1160, optional input/output 1150, input device(s) 1170, and wireless transceiver(s) 1130. It will be appreciated that additional components, not shown in FIG. 11, may also be a part of the data processing system 1100 in certain embodiments of the invention, and in certain embodiments of the invention fewer components than shown in FIG. 11 may be used. In addition, it will be appreciated that one or more buses, not shown in FIG. 11, may be used to interconnect the various components as is well known in the art.

The memory 1110 may store data and/or programs for execution by the data processing system 1100. The audio input/output 1140 may include a microphone and/or a speaker to, for example, play music and/or provide telephony functionality through the speaker and microphone. The display controller and display device 1160 may include a graphical user interface (GUI). The wireless (e.g., RF) transceivers 1130 (e.g., a WiFi transceiver, an infrared transceiver, a Bluetooth transceiver, a wireless cellular telephony transceiver, etc.) may be used to communicate with other data processing systems. The one or more input devices 1170 allow a user to provide input to the system. These input devices may be a keypad, keyboard, touch panel, multi touch panel, etc. The optional other input/output 1150 may be a connector for a dock.

Apparatus and Method for Preventing Program Code Injections

Existing web integrity protection methods such as Content Security Policy (CSP) and Subresource Integrity (SRI) can protect the integrity of external elements referenced by the main Hypertext Markup Language (HTML) page. However, they only work if they are supported by the client and the main HTML page wasn't subject to a man-in-the-middle (MITM) attack while loading. Existing protection technologies such as Public Key Pinning, Certificate Transparency and even Token Binding do not provide full protection against such attacks.

When submitting the FIDO/Web Authentication response, a technology such as Token Binding is required, allowing the server to verify that the resulting authenticated session would be owned by the client connected to the authenticator and not by some third party such as the MITM attacker.

Malicious JavaScript is often injected as a result of a man-in-the-middle attack, where the browser attempts to fetch a resource from a specific URL, but instead ends-up fetching a modified resource from a malicious server. FIG. 12 illustrates an example in which the MITM 1211 intercepts communication between a client/browser 1210 and a server 1212.

Browsers use the domain name service (DNS) to resolve server names to IP addresses and they use Transport Layer Security (TLS) to authenticate the server and encrypt the traffic exchanged between the client and the server. Servers are authenticated using TLS Server certificates issued by TLS Certificate Authorities (CAs) that are trusted by the clients. Unfortunately, TLS CAs sometimes maliciously issue certificates to attackers and sometimes attackers are able to obtain the relying party's TLS certificate private key. For example, in FIG. 12, the MITM 1211 might use a maliciously issued certificate for server.com or a stolen certificate & private key from server.com.

Public Key Pinning has been designed to protect against maliciously issued TLS server certificates but it has several downsides that prevent large-scale adoption. Certificate Transparency has been proposed to fix these downsides, but it is not yet widely supported and has some weaknesses as well.

In contrast to Public Key Pinning (PKP) and Certificate Transparency (CT), the Token Binding approach allows the server to learn whether the client talks to the right entity or not. In the case of PKP and CT the server has to trust the client implementing support for that approach. Unfortunately, Token Binding alone is not sufficient to effectively provide MITM protection. For example, typical web pages include JavaScript code from potentially multiple sources (e.g. Google's IMA SDK, Google Analytics, etc.) and Token Binding data is only checked when receiving the authentication response. Accessing the sign-in page is always possible without any user authentication.

FIDO and Web Authentication provide a simple and secure way to authenticate users in web environments (and other environments). The Web Authentication specification includes support for Token Binding (RFC8471) in order to add robust protection against exporting and replaying security/session tokens by man-in-the-middle (MITM) attackers.

FIG. 13 illustrates a sequence of a typical website load process. The client loads the main HTML file upon selecting the link to the server 1311. The main JavaScript file is then loaded. The client then transmits an authentication response and the server returns protected (e.g., data that is only accessible after successful authentication) content.

In reality, typical web pages consist of two or more elements to be loaded by the client 1310. There is only one token binding data included in the Web Authentication assertion—the one related to the connection when sending the authentication response.

As indicated in FIG. 14, this means that a MITM 1412 attack when loading the main HTML file or when loading the main JS file (both of which are available to unauthenticated clients) would not be detected by the server 1311 when verifying the Token Binding data in the Web Authentication response. As a consequence, attackers can inject malicious JavaScript code and/or tamper with potential integrity protection policies.

The risk of loading external objects which have been tampered with has been identified by the Web App Security community and two main approaches against these types of attacks have been developed.

One approach, Subresource Integrity (SRI), allows the specification of the expected hash values for external resources in the HTML code using the “integrity” attribute. Under the assumption that the main web page was loaded without any tampering, SRI lets the Browser refuse and potentially notify the server when loading tampered with subresources required by this web page. Many Browsers support SRI today. Unfortunately, there is no secure way for the client 1310 to notify the server 1311 about implemented support for SRI, nor is there a way for the client 1310 to notify the server 1311 about the received SRI “integrity” attributes when loading the main HTML page. The reason is that the malicious JavaScript can always trigger the same notification calls. As a consequence, a MITM attacker 1412 could modify the SRI “integrity” attributes when loading the main HTML page.

Another approach is the Content Security Policy (CSP) which is specified in the HTTP header and allows relying parties to specify a list of trusted sources for external objects, such as Javascript code. A hash value of such code may also be specified. Unfortunately, it doesn't provide methods to protect against MITM attacks on the policy itself. When the loading of the main HTML file is already subject to a MITM attack, the Content Security Policy can be maliciously weakened. Additional weaknesses of CSP have also been revealed.

The general disadvantage of CSP, SRI, and similar approaches is that the server 1311 cannot learn (1) whether the client 1310 actually supported these concepts and verified the contents and (2) whether the fetched main web page (potentially fetched through a MITM 1412) really contained the correct integrity protection policy.

Note that even when the client loaded the main HTML page with perfect CSP and SRI support, Token Binding support is still required in Web Authentication to provide robust MITM protection. Referring to FIG. 15, if the MITM 1512 targets the transmission of the authentication response from the client 1310, the MITM 1512 would then own the authenticated session. Such an attack will not rely on modified HTML code, modified CSP or SRI policies nor on modified JS code. DNS poisoning and access to the stolen TLS server certificate private key (in the case of Certificate Transparency support) or access to a maliciously issued TLS server certificate to the MITM 1412 for the server's domain (in the case of missing Certificate Transparency support) is sufficient.

Unfortunately, Token Binding support in Web Browsers is rare. As a result, reaching an Authentication Assurance Level such as AAL3 (NIST 800-63) with web applications is impractical today.

An additional challenge for entities with a need for high security is that they typically need to be able to control the computing environment as much as possible. This also means that they need to know whether the (not corrupted) client 1310 implements security measures and they typically want contractual relationships with all parties they depend on. Signing bilateral contracts with each TLS CA or browser vendor that defines the list of acceptable TLS CAs seems rather impractical.

Referring to FIG. 16, to address these limitations, one embodiment of the server 1611 includes a client evaluator 1650 to assess the security characteristics of the dynamically-loaded code executed on the client 1610. One embodiment implements the following countermeasures to address the limitations described above. First, the client evaluator 1650 determines the integrity protection measures the client 1610 supports. In addition, a Web page evaluator 1652 determines the integrity protection policy (e.g. CSP or SRI) that was imposed by the web page and also evaluates the web page to determine whether web page was tampered with. In addition, the web page evaluator may be provided with access to and/or determine the hash values of all external objects associated with the web page, which is relevant in the case of missing CSP and SRI support.

One embodiment implements Token Binding support allowing the server 1611 to verify whether the authentication response was received directly from the client 1610 which includes the authenticator 1630 or indirectly through some MITM. Details of the client 1610 and the server 1611 will now be provided in accordance with the embodiments of the invention.

I. Client 1610

One embodiment of the client 1610 authentication engine 1613 includes extensions to the Web Authentication Data (WAD) dictionary 1620 (e.g., the CollectedClientData dictionary in existing Web authentication specifications) or to the TokenBinding Extension including a list of supported integrity protection capabilities 1620A and the associated version numbers (e.g. CSP, SRI, CertificateTransparency, Token Binding, etc). In addition, one embodiment of the WAD dictionary 1620 includes a list of resource descriptors 1620B associated with the loading of a web page, where each resource descriptor includes one or more of the following elements:

-   -   a. A sequence number related to the order of processing the         corresponding resource. For example, the primary HTML page may         have the sequence number 1 and the first external resource that         is processed will have sequence number of 2, and so on.     -   b. The URL from which the resource was loaded (e.g.         “https://www.rp. com/index.html”,         “https://panopticum.com/tracker.js”, etc.).     -   c. The hash value of the potential integrity policy instructions         included in the HTTP header (e.g., of the CSP policies).     -   d. The type of the element associated with the resource (e.g.,         Javascript, HTML, Image, Web Assembly, etc.).     -   e. The actual hash of the entire element/file computed by the         client, including the first byte to the last byte.     -   f. The expected hash of the element (e.g., as specified using         the SRI “integrity” attribute).     -   g. A list of code descriptors 1620C may also be included for         each resource descriptor 1620B, potentially with one entry per         JavaScript/WebAssembly code fragment in this object, each         containing one or more of the following elements:         -   1. The actual hash of the element computed by the client             (e.g. hash of the real code between <script>and             </script>tags, or the entire string of the code if assigned             to an attribute),         -   2. A tag associated with each code fragment (e.g., “script”             in the case of code being included in script tags, “body”,             “frame”, “img”, “input”, etc. if the code is included in an             attribute of such tags).         -   3. A related “ID” of the tag if it was specified.         -   4. A related attribute, if the code was specified in such an             attribute (e.g., an “onload” attribute, “onclick” attribute,             etc).

In one embodiment, all code that is loaded into the context of that web page is included for evaluation by the authentication engine 1613 and the server-side authentication engine 1650. For example, all HTML elements and code fragments that have been processed (but not necessarily executed) at the time of the “get”/“create” call may be included. Sometimes, code is dynamically loaded such as when a user clicks on an element. In one implementation, such code fragments are only included if they have been loaded at the time of the “get”/“create” call.

In the case existing JavaScript code dynamically adds new JavaScript code elements, those dynamically added elements are also included as entries in the list of code descriptors 1620C. These code descriptors for dynamically generated code on the client side are related to dedicated resource descriptor having an empty URL (since that resource was dynamically generated and not directly loaded from a remote source).

II. Server 1611

As illustrated in FIG. 16, the authentication engine 1650 on the server 1611 may authenticate the client using any portion of the extended WAD dictionary 1620 including the integrity protection capabilities 1620A, the resource descriptors 1620B, and/or the code descriptors 1620C. The integrity protection capabilities 1620A may be evaluated by a client evaluator component 1651 of the authentication engine 1650 and the resource descriptors 1620B and code descriptors 1620C may be evaluated by a web page evaluator component 1652. For example, in one embodiment, the web page evaluator 1652 maintains a set of data related to expected resource descriptors 1652B and expected code descriptors 1652C. The authentication engine 1650 on the server 1611 may then compare authentication data received from the client 1610 (e.g., signatures, hash values, etc., based on the resource descriptors 1620B and/or code descriptors 1620C) with its own data associated with the expected resource descriptors 1652B and code descriptors 1652C. Relying parties that are interested in this extra layer of security may implement different approaches to verify the correctness of the loaded (JavaScript) code.

If the authentication engine 1650 on the server 1611 implements a “strict” approach, the expected entries of all Resource Descriptors 1620B and Code Descriptors 1620C may be determined and compared. Javascript code may be limited to a well-defined number of external files with a given hash value. This approach might be implemented by entities with high security requirements and by servers implementing the specifications in a straight-forward way.

A machine learning approach is used in one embodiment of the authentication engine 1650. For example, the machine learning-based authentication engine 1650 may check for support of integrity protection measures 1620A, check the integrity of the integrity protection policy instructions associated with those measures, and/or check for pairs of file names and related hash values in the list of Code Descriptors 1620C that appear the first time or very rarely (e.g., which could indicate a spear phishing attack). These situations could then be handled in a similar manner to analysis of virus patterns by antivirus scanners today—i.e., the transaction may be flagged as “high-risk” which then triggers the authentication engine to implement additional protective measures.

One advantage of the above is the fact that this approach does not penalize/hurt relying parties that are not interested in such a level of security. Those relying parties would simply ignore the additional data elements. These embodiments are also compatible with current web practices, like loading third party Javascript code from other URLs. It does not require those third parties to add code signatures or otherwise change their code. Relying parties requiring a high security level can use the above embodiments and implement strict checking—limited to the applications/web pages that require such a level of protection.

Relying parties that are interested in a machine learning based approach could still leverage existing third-party Javascript modules—without expecting such ecosystem partners to implement additional security levels. Expected hash values of such modules do not have to be included in the file directly (as such would require dynamic generation). Instead the verification may be done by a FIDO server when verifying the authentication response.

This approach is also compatible with dynamically generated HTML as verification of the entire (potentially dynamically generated) HTML object is not required. The security-relevant parts of the resulting document object model (DOM) tree can be verified dynamically by Javascript, if the unmodified Javascript is executed.

The above approach also leverages the cryptographic signature capabilities of authenticators 1613 of the client 1610. This is the way to provide a proof to the server 1611 of what web page is loaded and rendered by the client 1610 (as the client itself has no cryptographic secret that could be used to authenticate any information provided back to the server).

This approach is also privacy friendly. The additional data elements do not contain personal information nor personal identifying information of the user; only the data related to the contents of the loaded web page. Those web pages without a need for user authentication won't see the additional data elements and those web pages with a need for user authentication may use the additional data elements for verifying the integrity of the loaded web page.

One embodiment of the invention includes a tool that analyzes web pages regularly given a set of sign-in URLs, creates a list of expected code fragments and their hash values, and creates a proposed integrity protection policy (CSP).

In one implementation, a repository of known-good JavaScript URLs and hash values are initially provided in a repository. Code fragments and values that appear on the Internet may be synchronized with this repository to maintain a “known-good” state. One embodiment includes Javascript code that verifies the security relevant parts of the document object model based on the web pages which are regularly analyzed.

In one embodiment, a JavaScript secureLoad function is provided in the form of a software development kit (SDK). This secureLoad function verifies the loaded object against an expected hash value that is provided as a parameter. Such a function simplifies a secure approach to dynamically load external resources (e.g. images, text, JS, . . . ) using a Javascript function.

These embodiments of the invention may also be extended to other areas in which the client device can be assumed to be secure and does not directly support attestation. The client device is also assumed to have access to a module/device that can generate a cryptographic assertion (like a FIDO Authenticator or a TPM) and allows the execution of arbitrary code loaded from various sources that potentially could be infected/modified. One example is an IoT device supporting execution of custom code.

One embodiment of the invention comprises a client with a web browser or other software that loads content and program code from web servers or other external entities. The client/browser interfaces with a trusted entity capable of signing a cryptographic assertion (e.g. a FIDO Authenticator) that includes one or more resource descriptor 1620B and/or code descriptor 1620C objects in the cryptographic computation. For example, one embodiment includes a cryptographic hash value of such resource descriptor(s)/code descriptor(s) in the to-be-signed object.

In addition, one embodiment includes a server-side component such as a FIDO server which verifies the cryptographic assertion and verifies that the cryptographic assertion only includes those resource descriptors 1620B and/or code descriptors 1620C that have been specified as expected resource descriptors. The authentication engine may return a risk score indicating how likely it is that malicious resource descriptors and/or code descriptors have been found.

One embodiment includes a server-side software component, such as the authentication engine 1650 (e.g. a FIDO Server) verifying the cryptographic assertion and verifying that the cryptographic assertion only includes resource descriptor(s)/code descriptor(s) that the server has already seen multiple times from trusted locations before (e.g. using Machine Learning to determine what “multiple times” means and what “trusted locations” are). The software component returns a risk score indicating how likely it is that malicious resource descriptors/code descriptors have been found.

One embodiment of the invention includes a software tool that loads relevant web pages through an internal channel protected against MITM attacks (e.g. the ones used for sign-in) to learn what resources and code fragments are typically being used. This software tool automatically feeds a database of Expected Resource Descriptors/Expected Code Descriptors plus the related source code in the clear for web sites that can be used by the server-side authentication engine.

A JavaScript function that can be included by a web site to be executed by the client to verify that the security-relevant parts of a DOM tree have not been modified by an attacker (e.g., whether the “Buy Now” button still exists and is the only element with the given ID, whether elements to show the contents of a transaction exist in the DOM tree and are visible to the user, whether dynamically generated Javascript code follows a specific pattern, etc.). Any of the techniques described above may be used to validate the Javascript code.

In one embodiment, a feedback function is implemented in the server-side authentication engine that uploads the resource descriptors/code descriptors of maliciously found Javascript code on the web to a central server maintaining a list of malicious resource descriptors/code descriptors.

One implementation includes a software tool that analyzes a list of malicious resource descriptors/code descriptors (e.g., collected as described above), to create “patterns” that can help identify similar (but not exactly the same) code fragments (e.g. some internal variables renamed, slight modification of the internal order or structure, etc.). The software tool may analyze a list of resource descriptors/code descriptors and load the related source code from the URLs given in those resource descriptors/code descriptors in order to verify whether such code matches the one or more patterns.

One embodiment also includes a software SDK that allows the secure loading of external resources like images, text or code (e.g. Javascript, WebAssembly, . . . etc). This SDK receives the URL and the expected hash value of that resource. Alternatively, or in addition, the SDK receives the URL and a trust anchor (e.g. code signing certificate, code signing CA certificate, or root certificate) to verify the code signature of external resources to be loaded.

Embodiments of the invention may include various steps as set forth above. The steps may be embodied in machine-executable instructions which cause a general-purpose or special-purpose processor to perform certain steps. Alternatively, these steps may be performed by specific hardware components that contain hardwired logic for performing the steps, or by any combination of programmed computer components and custom hardware components.

Elements of the present invention may also be provided as a machine-readable medium for storing the machine-executable program code. The machine-readable medium may include, but is not limited to, floppy diskettes, optical disks, CD-ROMs, and magneto-optical disks, ROMs, RAMs, EPROMs, EEPROMs, magnetic or optical cards, or other type of media/machine-readable medium suitable for storing electronic program code.

Throughout the foregoing description, for the purposes of explanation, numerous specific details were set forth in order to provide a thorough understanding of the invention. It will be apparent, however, to one skilled in the art that the invention may be practiced without some of these specific details. For example, it will be readily apparent to those of skill in the art that the functional modules and methods described herein may be implemented as software, hardware or any combination thereof. Moreover, although some embodiments of the invention are described herein within the context of a mobile computing environment, the underlying principles of the invention are not limited to a mobile computing implementation. Virtually any type of client or peer data processing devices may be used in some embodiments including, for example, desktop or workstation computers. Accordingly, the scope and spirit of the invention should be judged in terms of the claims which follow.

Embodiments of the invention may include various steps as set forth above. The steps may be embodied in machine-executable instructions which cause a general-purpose or special-purpose processor to perform certain steps. Alternatively, these steps may be performed by specific hardware components that contain hardwired logic for performing the steps, or by any combination of programmed computer components and custom hardware components. 

We claim:
 1. An apparatus comprising: a processor to execute an application to access a web page on the Internet in response to user input, the web page having one or more resource descriptors and/or code descriptors associated therewith; an authentication engine to validate the web page based, at least in part, on the resource descriptors and/or code descriptors, by connecting to a trusted entity; and wherein the trusted entity is configured to generate a signature on a cryptographic assertion that includes one or more resource descriptor objects associated with the one or more resource descriptors and/or one or more code descriptor objects associated with the one or more code descriptors.
 2. The apparatus of claim 1 wherein the authentication engine is to validate the web page using the signature on the cryptographic assertion.
 3. The apparatus of claim 1 wherein the signature comprises a cryptographic hash value of the one or more resource descriptors and/or code descriptors.
 4. The apparatus of claim 1 wherein the trusted entity comprises a server running a server-side authentication engine to verify the cryptographic assertion including verification that the cryptographic assertion only includes those one or more resource descriptors and/or code descriptors specified as expected resource descriptors and/or code descriptors.
 5. The apparatus of claim 4 wherein the server-side authentication engine is to responsively generate a risk score indicating a likelihood that malicious resource descriptors and/or code descriptors have been identified.
 6. The apparatus of claim 5 wherein the server-side authentication engine comprises a machine learning engine to verify that the cryptographic assertion only includes resource descriptors and/or code descriptors previously observed a determined number of prior times from a determined set of trusted locations, wherein the machine learning engine is to perform machine learning to continually update the determined number of prior times and the determined set of trusted locations.
 7. The apparatus of claim 6 wherein the processor is to execute program code comprising a function included in the web page to verify that one or more security-relevant portions of a document object model (DOM) tree have not been modified, the program code to be validated using the signature.
 8. A server apparatus comprising: an interface to receive an authentication request from a client; and an authenticator engine to generate a signature on a cryptographic assertion that includes one or more resource descriptor objects associated with one or more resource descriptors of a web page received by the client and/or one or more code descriptor objects associated with the one or more code descriptors of the web page; and the authenticator engine to transmit the signature to the client over the interface for validation of the web page.
 9. The server apparatus of claim 8 wherein the authenticator engine or an authenticator engine on the client is to validate the web page using the signature on the cryptographic assertion.
 10. The server apparatus of claim 8 wherein the signature comprises a cryptographic hash value of the one or more resource descriptors and/or code descriptors.
 11. The server apparatus of claim 8 wherein the authentication engine is configured to verify the cryptographic assertion including verification that the cryptographic assertion only includes those one or more resource descriptors and/or code descriptors specified as expected resource descriptors and/or code descriptors.
 12. The server apparatus of claim 11 wherein the authentication engine is to responsively generate a risk score indicating a likelihood that malicious resource descriptors and/or code descriptors have been identified.
 13. The server apparatus of claim 12 wherein the authentication engine comprises a machine learning engine to verify that the cryptographic assertion only includes resource descriptors and/or code descriptors previously observed a determined number of prior times from a determined set of trusted locations, wherein the machine learning engine is to perform machine learning to continually update the determined number of prior times and the determined set of trusted locations.
 14. The server apparatus of claim 13 wherein the client comprises a processor to execute program code comprising a function included in the web page to verify that one or more security-relevant portions of a document object model (DOM) tree have not been modified, the program code to be validated using the signature.
 15. A method comprising: receiving an authentication request from a client; and identifying a cryptographic assertion including one or more resource descriptor objects associated with one or more resource descriptors of a web page received by the client and/or one or more code descriptor objects associated with the one or more code descriptors of the web page; and generating a signature over the cryptographic assertion, the signature usable to validate the web page; and transmitting the signature to the client for validation of the web page.
 16. The method of claim 15 wherein the authenticator engine or an authenticator engine on the client is to validate the web page using the signature on the cryptographic assertion.
 17. The method of claim 15 wherein the signature comprises a cryptographic hash value of the one or more resource descriptors and/or code descriptors.
 18. The method of claim 15 wherein the authentication engine is configured to verify the cryptographic assertion including verification that the cryptographic assertion only includes those one or more resource descriptors and/or code descriptors specified as expected resource descriptors and/or code descriptors.
 19. The method of claim 18 wherein the authentication engine is to responsively generate a risk score indicating a likelihood that malicious resource descriptors and/or code descriptors have been identified.
 20. The method of claim 19 wherein the authentication engine comprises a machine learning engine to verify that the cryptographic assertion only includes resource descriptors and/or code descriptors previously observed a determined number of prior times from a determined set of trusted locations, wherein the machine learning engine is to perform machine learning to continually update the determined number of prior times and the determined set of trusted locations.
 21. The method of claim 15 wherein the client comprises a processor to execute program code comprising a function included in the web page to verify that one or more security-relevant portions of a document object model (DOM) tree have not been modified, the program code to be validated using the signature. 